The present invention relates to a rapid emergency dam, and is concerned particularly, although not exclusively, with an emergency flood water barrier.
During adverse weather conditions heavy rain can lead to rivers breaking their banks and lakes overflowing causing flooding to the surrounding countryside. Coastline defenses can also be breached by increased sea swell and large waves. The main form of defense against such flooding is to build a physical barrier constructed from sand bags. However, there is often little warning of flooding and the transport communications to remote locations can delay, or even prevent, the raw materials for the sand bags being delivered in time.
Another situation where a fluid barrier is required at short notice is where there has been a chemical or oil leak. In such cases it is important to prevent the spillage from spreading into neighbouring water supplies.
A barrier system may also be required to prevent the flow of particle matter such as snow or sand. A mass of small particles can move in a fluid-like manner. The movement of both snow and sand can have fluid characteristics. It is also desirable to be able to quickly erect a barrier system to prevent the movement of such matter.
U.S. Pat. No. 4,136,995 discloses a barrier comprising a plurality of spaced-apart A-frames positioned behind a barrier sheet, the barrier sheet being inclined in the direction away from an apron and from the expected flood water attack. On exposure to flood water, the A-frames substantially support the forces applied to the barrier sheet.
U.S. Pat. No. 5,605,416 discloses a foam-filled barrier structure of triangular cross-section and incorporating an apron.
U.S. Pat. No. 5,039,250 discloses a self-supporting folded stiff mesh structure for sediment control and which is capable of being furled and unfurled. In FIG. 1, supporting ribs are provided which have lower ends can be pushed into the ground to provide anchorage for the barrier.
None of these barriers is suitable to withstand the large forces associated with a flood of fluid. The present invention is directed at the problem of providing a furlable barrier structure that can be relatively quickly erected, is self-supporting when erected to await a flood, and which on exposure to a flood is capable of withstanding the forces applied by fluid pressure.
According to the invention a furlable fluid barrier section comprising a fluid barrier sheet for preventing the flow of fluid across ground, comprising lower and upper edges; an apron that is fluid impermeably connected to the lower edge of the fluid barrier sheet and extending from the lower edge in a direction facing the flow of fluid wherein the fluid barrier section is free standing when ready for use, support means for holding the fluid barrier sheet above the ground at an angle over the apron to define an open structure which is adapted to receive the flow of fluid, wherein, in use, the weight of the fluid on the apron provides a downward force on the apron; tie means adapted to connect to the upper edge of the barrier sheet; and a tie anchorage adapted to connect the apron to the tie means; wherein the apron, the tie means and the barrier sheet form a triangle in the transverse cross-section of the barrier section.
Preferably in use anchoring means for the fluid barrier section is substantially provided by the mass of a fluid on the apron.
The term xe2x80x98fluidxe2x80x99 used herein refers to any type of liquid or particulate matter that behaves in a fluid-like manner such as, but not limited to, snow, earth, mud or sand.
Preferably in use anchoring means for the tie means is substantially provided by the mass of a fluid on the apron.
Preferably the fluid barrier section comprises a porous panel that extends downwardly from the uppermost edge of the fluid barrier sheet in a direction towards the apron so forming a tent-like structure over the apron.
Preferably, the tie means comprises a number of straps.
Alternatively, the tie means is provided by the porous panel.
Preferably the porous panel comprises a mesh structure.
The lowermost edge of the porous panel preferably forms a series of fluid openings providing fluid communication to the inner space of the tent-like structure.
The support means is preferably a plurality of support members in the form a series of inverted V-shapes of which one side of the respective inverted V-shapes extends across the fluid barrier sheet. Preferably the second side of the respective inverted V-shapes extends across the porous panel.
In use the support members allow the fluid barrier section to be free standing.
Preferably the support members that extend across the fluid barrier sheet are provided with additional tie means to restrain the support members from deflection.
In an embodiment of the invention the fluid barrier section comprises a panel that extends downwardly from the uppermost edge of the fluid barrier sheet in a direction towards the apron so forming a tent-like structure over the apron, and the lowermost edge of the panel preferably forms a series of fluid openings providing fluid communication to the inner space of the tent-like structure
Preferably, the panel is made of the same material as the fluid barrier sheet.
It is preferable that the fluid barrier section is formed from a single flexible sheet having a first transverse fold line to form the apron and the fluid barrier sheet section; and a second transverse fold line at the apex of the tent-like structure to form the panel section.
Alternatively, the panel and fluid barrier sheet are both formed from a single flexible sheet wherein the panel is formed by the sheet being folded at the apex of the tent-like structure.
Preferably the respective support members are held within pockets attached to the fluid barrier sheet and pockets attached to the panel.
Preferably, the pockets attached to the panels provide the tie means.
Alternatively, the panel provides the tie means.
It is preferable that the fluid barrier section comprising additional tie means comprising a plurality of straps. Each strap preferably extends from the apron to a point between the ends of a support member that extend across the fluid barrier sheet.
Preferably each strap extends between a pair support members which form the inverted V-shape.
It is preferable that each strap extends from the mid-point of the first support member, that extend across the fluid barrier sheet, to the lowermost end of the second support member of a respective inverted V-shape. There is preferably a plurality of straps extending between each pair of support members forming the inverted V-shape.
In an alternative embodiment of the present invention the support means is a plurality of support members, each member being in the form of a L-shape of which one side of the respective L-shape extends across the fluid barrier sheet. Preferably the second side of the respective L-shape extends across the apron.
Preferably the apron comprises edge anchoring means, the arrangement being such that, in use, said means substantially prevents the edge of the apron from lifting under the influence of the advancing fluid.
The edge anchoring means preferably comprises anchoring pegs placed through respective holes formed in the edge margin of the apron.
Alternatively the anchoring means comprises a mass disposed on the edge of the apron.
Preferably the mass comprises a flexible chain or cord disposed on the edge of the apron.
Preferably the apron further comprises a margin of material of a lesser thickness than the thickness of the main region of the apron. One edge of the apron preferably comprises the anchoring means. Once erected the length of the apron from the lowermost edge of the fluid barrier sheet is preferably greater than the height of the fluid barrier sheet from the ground. Preferably the length of the apron is up to ten times the height of the fluid barrier sheet.
The side edges of the margin preferably comprise attachment means, the arrangement being such that in use the attachment means secures together the respective adjacent edges of adjacent fluid barrier sections so forming a fluid seal there between.
Preferably, the fluid barrier section provides fluid energy absorbing means, the arrangement being such that in use a fluid barrier section is capable of absorbing a force exerted on the fluid barrier sheet by a fluid.
Preferably, the fluid barrier section provides fluid energy damping means, the arrangement being such that in use a fluid barrier section is capable of damping a force exerted on the fluid barrier sheet by a fluid.
The barrier sheet may comprises a sheet of mesh netting that extends downwardly from the apex of the inverted V-shaped support members.
In use the sheet mesh netting allows liquid and gasses to pass there through whilst substantially preventing particle matter such as silt, sand and/or snow from passes through the mesh netting structure.